An Auckland medical centre's beating the odds to stay open as power outages plague the region.

Waimauku Doctors says thieves used bolt cutters to steal its $9,000 generator early this morning.

Administrator Kathleen Kerr says it was a scramble today to borrow a replacement while nearby Silver Fern Medical Centre remains closed.

Waimauku Doctors administrator Kathleen Kerr says both centres serve around 7,000 people in the community.

"A bit of a blowout for us this morning. We really were trying to keep functioning to support a lot of sick people. We have a lot of elderly [patients]."

Police are appealing to the public for any information about the stolen generator.